Clutch "flare"

[Weeberone]

Hi, my 1990 has what a GM service technician called a flare. He drove the car up a slight hill in fourth gear at about 1200rpm and applied moderate gas. The clutch seemed to slip a little and the rpm increased a couple hundred rpm as the car got up to speed and then held fine. This is unusual as the clutch works great in all other conditions including extreme acceleration from a standing start.
My question is; does the entire clutch need to be replaced, meaning flywheel, disk and pressure plate, or just, say, the disk etc?
Any help would be appreciated.

[kluketic]

Sounds like the clutch needs to be replaced. Knowing how many miles are on the car, and hard its been driven might be helpful but may not make any difference. I believe these are hydraulic throwout bearings, so probably no adjustment possible there.
If it were my car I would replace the clutch, pressure plate and throwout bearing as a unit, as i believe most would recommend.
Flywheel, if not scored, could just be resurfaced. Some may advocate replacing the flywheel with a high performance unit while your doing the clutch. No big advantage to this unless you're looking to ring every bit of power out of the car you can.

[Flyman 27]

The only work that should be done to the flywheel is a mild application of scotchbright pads. You do NOT want to "resurface" a dual mass flywheel.
The little shavings can easily get into the working parts of the flywheel and then it is a boat anchor.
About 18 months ago I was going to Mark's to swap my clutch. The flywheel had been "resurfaced" and there were chips in the mechanism, which was evident by turning the wheel & hearing the grinding of little chips.
Mark said this was common in flywheels that had been machined.
I had 2 flywheels that were bad for this reason.
I ended up using an old rusty flywheel from a friend (thanks Paul!). It cleaned up nicely with a little scotchbright.

[Weeberone]

If the flywheel is ok and just needs a little scotch brite, then only the other components could be replaced? Any opinions on this set up?

https://www.summitracing.com/parts/l.../submodel/zr-1

[kluketic]

By"resurfacing" I didn't necessarily mean turning it. But I would definitely check the flywheel for warpage with a dial indicator.
I have no experience with Summit's clutch kit offering.

[Ccmano]

Originally Posted by kluketic

By"resurfacing" I didn't necessarily mean turning it. But I would definitely check the flywheel for warpage with a dial indicator.
I have no experience with Summit's clutch kit offering.

Keep in mind the flywheel has a “cup” designed into the surface.

Best article on the subject by Mark Haibeck

http://www.zr1specialist.com/HAT%20W...0in%202019.pdf

H

[A26B]

Originally Posted by Ccmano

Keep in mind the flywheel has a “cup” designed into the surface.

Best article on the subject by Mark Haibeck

http://www.zr1specialist.com/HAT%20W...0in%202019.pdf

H

Hans,
You mentioned "the flywheel has a "cup" designed into the surface. Several months ago, I was inspecting several OE DMF's. All still have the machine tooling marks present. I found that they had about 0.005" ~ 0.006" "dish" or "cup" as you prefer, down towards the center. Do you mind telling me where you derived your statement? I have been hesitant to sell either of these flywheels and your comment is the first I have heard of this.

I read Marc's document from the link you posted. He mentions the pressure plate having an 0.008" cup, but nothing about the flywheel.

Thanks,
Jerry

[Ccmano]

Originally Posted by A26B

Hans,
You mentioned "the flywheel has a "cup" designed into the surface. Several months ago, I was inspecting several OE DMF's. All still have the machine tooling marks present. I found that they had about 0.005" ~ 0.006" "dish" or "cup" as you prefer, down towards the center. Do you mind telling me where you derived your statement? I have been hesitant to sell either of these flywheels and your comment is the first I have heard of this.

I read Marc's document from the link you posted. He mentions the pressure plate having an 0.008" cup, but nothing about the flywheel.

Thanks,
Jerry

Jerry,
Haibecks article quoted here does have that statement. He says the flywheel has a “cup” of 0.010”. Page 4 under the paragraph that leads with “Inspection of the Dualmass Flywheel “
H

[A26B]

Originally Posted by Ccmano

Jerry,
Haibecks article quoted here does have that statement. He says the flywheel has a “cup” of 0.010”. Page 4 under the paragraph that leads with “Inspection of the Dualmass Flywheel “
H

Your are absolutely right! I only read the first page & thought that was the entirety of it. I will have to ask Marc where he obtained the flywheel cup information.

[Weeberone]

Thanks! That article is exactly the information I’m looking for.

How does one determine the difference between needing just a new friction disk and needing a new flywheel and pressure plate too?